JP2007201233A - Light-emitting module, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light-emitting module having excellent processability by employing a lead frame, an insulator, an optically reflective material and a metal plate instead of a ceramic substrate, and to provide a manufacturing method thereof. <P>SOLUTION: In the light-emitting module, one part equivalent to a terminal of the lead frame 100 is formed into a first convex portion 114, one part of the lead frame 100 is covered with an optically reflective material 104, a light-emitting element 108 is mounted, and the lead frame 100 is molded integrally with a metal plate 112 having a second convex portion 116 via a thermally conductive resin 102. With this configuration, a light to be emitted from a light-emitting element 108 is reflected on the optically reflective material 104 and a reflection section 118, and heat generated from the light-emitting element 108 is transmitted from the lead frame 100 to the metal plate 112 via the thermally conductive resin 102. Thus, the light-emitting efficiency and heat radiating efficiency of the light-emitting module can be improved. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting module used for a backlight of a display device having a backlight such as a liquid crystal television and a manufacturing method thereof.

  Conventionally, a cold cathode tube or the like has been used for a backlight of a liquid crystal television or the like, but in recent years, it has been proposed to mount a semiconductor light emitting element such as an LED or a laser on a heat dissipating substrate ( For example, see Patent Document 1).

  FIG. 9 is a cross-sectional view showing an example of a conventional light emitting module. In FIG. 9, the light emitting element 2 is mounted in the recess formed in the ceramic substrate 1. The plurality of ceramic substrates 1 are fixed on the heat sink 3. Further, the plurality of ceramic substrates 1 are electrically connected by a connection substrate 5 having a window portion 4. The light 6 emitted from the LED is emitted to the outside through the window portion 4 formed on the connection substrate 5. In FIG. 9, the wiring in the ceramic substrate 1 having the recesses and the connection substrate 5, the LED wiring, and the like are not shown. Such light emitting modules are used as backlights for liquid crystals and the like. However, since the ceramic substrate 1 is difficult to process and expensive, there has been a demand for a heat dissipation substrate that is less expensive and has excellent workability.

  On the other hand, the display device side including the liquid crystal TV is desired to expand the color display range. In response to such needs, white LEDs and the like have limitations, and in recent years, red (red), green (green), and blue (blue) single-color light emitting elements, and further purple, orange, red purple, cobalt Attempts have been made to expand the color display range (specifically, the CIE color system, etc.) by adding a special color light emitting element that emits a special color such as blue.

  When such a light emitting module as shown in FIG. 9 is used to meet such needs, while mounting each of these light emitting elements one by one in the concave portion of the ceramic substrate 1, a uniform mixed color (colored and white) is produced as a whole, It is necessary to adjust the color balance (for example, white balance described later). On the other hand, it is known that the luminous efficiency of solid light emitting devices such as LEDs decreases as the temperature rises. Furthermore, the degree of decrease in luminous efficiency with respect to temperature varies depending on the emission color of the LED. For this reason, for example, immediately after the liquid crystal TV is turned on, the LED portion is at room temperature (for example, 25 ° C.), so even if white balance is maintained, the temperature of the LED portion increases (for example, 40 ° C. → 50 ° C.). → 60 ° C.), for example, a phenomenon such as a reduction in red light emission efficiency may occur, and color reproducibility and backlight luminance may also change.

  On the other hand, as shown in FIG. 9, when the ceramic substrate 1 on which the light emitting elements 2 such as LEDs are mounted one by one is arranged on the heat radiating plate 3, it is advantageous from the viewpoint of heat dissipation, while a filter or diffusion is used. It becomes difficult to produce a white color by mixing light using a plate or the like (or to produce a white color having high color rendering properties by mixing RGB + special colors).

Therefore, it is possible to mount a large number of light-emitting elements that can handle higher brightness of the light-emitting elements (necessary to pass a large current) and multi-LEDs (mounting a plurality of LEDs with high density). There is a demand for light-emitting modules that have high processability and excellent heat dissipation.
JP 2004-311791 A

  However, the conventional configuration has a problem that the heat dissipation substrate on which the light emitting element is mounted is a ceramic substrate, which is disadvantageous in terms of workability and cost.

  The present invention solves the above-described conventional problems, and provides a light-emitting module with good processability and a method for manufacturing the same by using a lead frame, an insulator, a light reflecting material, and a metal plate instead of a ceramic substrate. The purpose is to do.

  In order to solve the above problems, the present invention mounts a light emitting element such as an LED directly on a lead frame having high heat dissipation, and reflects light from the light emitting element by a ring-shaped reflecting portion. The generated heat is transmitted from the lead frame to the heat radiating metal plate formed on the back surface through the heat conducting resin.

  The light emitting module obtained by the light emitting module of the present invention and the manufacturing method thereof can efficiently diffuse the heat generated by the light emitting elements such as LEDs and semiconductor lasers, and can effectively cool the light emitting elements such as LEDs.

(Embodiment 1)
Hereinafter, the light emitting module in Embodiment 1 of this invention is demonstrated using FIG. 1, FIG.

  1A and 1B are a top view and a cross-sectional view illustrating a light-emitting module according to Embodiment 1, in which FIG. 1A is a top view, and FIGS. 1B and 1C are FIGS. It is sectional drawing in arbitrary parts. In FIG. 1, 100 is a lead frame, 102 is a heat conducting resin, 104 is a light reflecting material, 106 is an auxiliary line, 108 is a light emitting element, and the light emitting element 108 is a light emitting element such as an LED or a laser. Reference numeral 110 denotes an arrow indicating light emitted from the light emitting element 108, 112 denotes a metal plate, 114 denotes a first convex portion, and 116 denotes a second convex portion. A part of the lead frame 100 bulges partially in a convex shape, and this bulge is formed in a donut shape. In addition, the second protrusion 116 is formed such that a part of the metal plate 112 bulges partially in a convex shape, and this bulge is formed in a donut shape. Then, as shown in FIGS. 1A and 1B, the second convex portion 116 is fitted into the first convex portion 114 with the heat conductive resin 102 interposed therebetween.

  Reference numeral 118 denotes a reflection portion, which is formed on the lead frame 100 in a ring shape (so as to surround the light emitting element 108 in FIG. 1A). In the first embodiment, the lead frame 100 fixed by the light reflecting material 104 is further insulated and fixed on the metal plate 112 via the heat conducting resin 102. A ring-shaped reflecting portion 118 that is slightly smaller is formed in the ring of the first convex portion 114 formed by the lead frame 100. Then, the light emitted from the light emitting element 108 is reflected by the reflection unit 118.

  First, description will be made with reference to FIG. In FIG. 1A, lead frames 100 are insulated from each other through a heat conductive resin 102 in a state of being divided into a plurality of parts. The auxiliary line 106 indicates the bending position of the lead frame 100, and the lead frame 100 and the metal plate 112 are bent at the position of the auxiliary line 106 in FIG. The first convex portion 114 and the second convex portion 116 as shown in FIG. 1C are formed, and the reflective portion 118 is set in the area surrounded by the convex portions, and the light emitting element 108 emits light. Reflects to the front. Note that the light emitting element 108 is formed so as to straddle the plurality of lead frames 100 (note that the light emitting element 108 does not necessarily have to be mounted straddling). Similarly, members such as a wire wire for mounting the light emitting element 108 (wire wire is in the case of wire bonding connection), conductive resin, solder (in the case of flip chip mounting, etc.) are not shown in FIG.

  Note that portions of the plurality of lead frames 100 on which the light emitting elements 108 are mounted are fixed by a light reflecting material 104 instead of the heat conducting resin 102. In addition, the periphery of the portion of the lead frame 100 where the light emitting element 108 is mounted is surrounded by a ring-shaped reflecting portion 118 made of the light reflecting material 104, and the light emitted from the light emitting element 108 passes through the gap between the lead frames. In addition to the light reflecting material 104 formed in (4), the light is reflected forward by the ring-shaped reflecting portion 118. As a result, the luminous efficiency increases.

  Next, description will be made with reference to FIG. FIG. 1B corresponds to a cross-sectional view at an arbitrary position in FIG. In FIG. 1B, a part of the lead frame 100 is a first convex portion 114. And the 1st convex part is formed under this 1st convex part 114 via the heat conductive resin 102. As shown in FIG.

  Further, by forming the ring-shaped reflecting portion 118 made of the light reflecting material 104, the light emitted from the light emitting element 108 is reflected by the reflecting portion 118 as shown by an arrow 110, and the luminous efficiency is increased.

  1C corresponds to a cross-sectional view at an arbitrary position in FIG. 1A as in FIG. 1B. As shown in FIG. 1C, the light emitted from the light emitting element 108 is reflected by the reflecting portion 118 formed of the light reflecting material 104 as indicated by an arrow 110. As shown in FIG. 1C, the light reflectance in the vicinity of the light emitting element 108 can be increased by forming the light reflecting material 104 between the lead frames 100. For this reason, even when a plurality of light emitting elements each having a different light emission color are mounted within the area surrounded by the ring-shaped light reflecting material 104 (or the reflecting portion 118), the mixed color (or white color due to the mixed color) can be obtained. Formation) can be facilitated.

  Next, a more detailed description will be given with reference to FIG. FIG. 2 is a view showing the shape of the lead frame, which corresponds to a shape obtained by removing the reflection portion 118 from FIG. From FIG. 2, it can be seen that the lead frame 100 is also formed under the ring-shaped reflecting portion 118. Further, it can be seen that the leading end portion of the lead frame 100 (or the vicinity of the portion where the light emitting element 108 is mounted) is fixed by the light reflecting material 104 (note that the light emitting element 108 is not shown in FIG. 2). As shown in FIG. 2, the light reflectance in the vicinity of the light emitting element 108 can be increased by forming the light reflecting material 104 between the lead frames 100. For this reason, even when a plurality of light emitting elements each having a different emission color are mounted within the area surrounded by the ring-shaped reflection portion 118, the color mixture (or white formation by color mixture) can be facilitated.

  Next, FIG. 3 illustrates how heat generated in the light emitting element 108 is diffused. FIG. 3 is a diagram illustrating how heat is diffused, in which the light emitting element 108 is omitted from FIG. In FIG. 3A, an arrow 110a is an arrow indicating a direction in which heat is transmitted from the light-emitting element 108 (not illustrated in FIG. 3). 3A that heat generated in the light emitting element 108 (not shown in FIG. 3) is diffused along the lead frame 100 in the direction of the arrow 110a.

  FIG. 3B is a cross-sectional view illustrating a state of heat diffusion in the cross section of FIG. 3B that heat generated in the light-emitting element 108 diffuses along the shape of the lead frame 100 in the direction of the arrow 110b.

  FIG. 3C is a cross-sectional view illustrating a state of heat diffusion in the cross section of FIG. From FIG. 3C, it can be seen that the heat transmitted to the lead frame 100 is diffused to the metal plate 112 through the heat conducting resin 102 as indicated by an arrow 110c.

As the heat conducting resin 102, it is desirable to use a resin in which a highly heat dissipating inorganic filler is dispersed in a curable resin. The inorganic filler has a substantially spherical shape, and its diameter is suitably from 0.1 to 100 microns (if it is less than 0.1 microns, it becomes difficult to disperse in the resin, and if it exceeds 100 microns, the heat conductive resin 102 is used. Increases the thickness of the material, affecting the thermal diffusivity). Therefore, the filling amount of the inorganic filler in the heat conducting resin 102 is filled at a high concentration of 70 to 95% by weight in order to increase the thermal conductivity. In particular, in the present embodiment, the inorganic filler is a mixture of two types of Al ₂ O ₃ having an average particle size of 3 microns and an average particle size of 12 microns. By using the Al ₂ O ₃ of the large and small two types of particle size, it is possible to fill the Al ₂ O ₃ of small particle size in the gap Al ₂ O ₃ of large particle size, Al ₂ O ₃ 90 wt% near Can be filled to a high concentration. As a result, the thermal conductivity of the heat conducting resin 102 is about 5 W / (m · K). The inorganic filler may include at least one selected from the group consisting of MgO, BN, SiO ₂ , SiC, Si ₃ N ₄ , and AlN instead of Al ₂ O ₃ .

  The thermosetting insulating resin contains at least one kind of resin among epoxy resin, phenol resin and cyanate resin. These resins are excellent in heat resistance and electrical insulation. If the thickness of the heat conducting resin 102 is reduced, the heat generated in the light emitting element 108 attached to the lead frame 100 can be easily transferred to the metal plate 112, but conversely, the insulation breakdown voltage becomes a problem, and if it is too thick, the thermal resistance increases. In view of the withstand voltage and thermal resistance, the optimum thickness may be set to 50 microns or more and 1000 microns or less.

  As described above, in the first embodiment, a filler having good thermal conductivity is added as the heat conductive resin 102, and a filler having excellent light reflectivity is added to the light reflecting material 104. (Or the formation of white light by mixing different monochromatic lights).

  Note that the color of the heat conducting resin 102 is desirably white. This is because when the color is black, red, blue, or the like, it is difficult to reflect the light emitted from the light emitting element, which affects the light emission efficiency.

  Note that the reflecting portion 118 is preferably ring-shaped (or donut-shaped). This is to increase the light reflection efficiency. Further, the shape of the side surface of the reflecting portion 118 can be formed so as to become narrower toward the bottom, which is to increase the light reflection efficiency. It goes without saying that the light reflection direction can be optimized by making the side surface of the reflecting portion 118 radial, quadratic curve, cubic curve or the like.

(Embodiment 2)
Hereinafter, an example of the manufacturing method of the light emitting module in Embodiment 2 of this invention is demonstrated using FIGS. 4-5 is sectional drawing which shows an example of the manufacturing method of the light emitting module in Embodiment 2, 120 is transparent resin and 122 is a lens.

  FIG. 4A is a cross section of the lead frame 100, and a part of the lead frame 100 is stamped with a fine pattern on a mounting portion of a light emitting element with a mold or the like.

  FIG. 4B is a cross-sectional view showing a state in which a part of the lead frame 100 is fixed by the light reflecting material 104. By fixing a part of the lead frame 100 with the light reflecting material 104, the deformation of the lead frame 100 can be prevented. In addition, as the light reflecting material 104, a resin material mainly including a white resin used for manufacturing an LED chip or the like (a white pigment is added as necessary) can be used. Since such a member can be injection-molded, the reflecting portion 118 can be formed on the lead frame 100 simultaneously with the fixing of the lead frame 100.

  FIG. 4C shows a state in which the first protrusion 114 is formed on a part of the lead frame 100. Similarly, the second convex portion 116 is formed on the metal plate 112 (not shown). By forming the first convex portion 114 in this way, the reflective portion 118 is protected, and when the light emitting element 108 is resin-sealed (as will be described later), the resin overflows and leaks from the light emitting module. Can be prevented. Next, using the heat conductive resin 102, the lead frame 100 on which the light reflecting material 104 and the first convex portion are formed and the metal plate 112 on which the second convex portion 116 is formed are integrally molded. In this integral molding, a press device using a mold can be used. Moreover, the heat conductive resin 102a can be hardened in a metal mold | die by heating at arbitrary temperature (for example, 180 degreeC), for example in the range of 80 to 200 degreeC.

  Note that the order of forming the first convex portion 114 and the reflecting portion 118 can be changed as necessary.

  FIG. 4D is a cross-sectional view after the lead frame 100 in which the light reflecting material 104 is molded and the metal plate 112 are fixed by the heat conductive resin 102. Next, as shown in FIG. 4E, the light-emitting element 108 is mounted. Here, the light-emitting element 108 can be mounted by any method such as solder mounting, wire bonder mounting, or flip chip mounting.

  Next, the transparent resin 120a is poured into the portion surrounded by the reflecting portion 118 and cured. As shown in FIG. 5A, the transparent resin 120a may be formed by appropriately filling the portion surrounded by the reflective portion 118. Moreover, the whole part enclosed by the reflection part 118 can be covered with the transparent resin 120a as needed. In this case, as shown in FIG. 5B, it is desirable to have a structure in which the transparent resin 120c overflowing from the reflecting portion 118 is received in the gap between the reflecting portion 118 and the lead frame 100. In this way, the process can be stabilized.

  FIG. 5C is a cross-sectional view showing a state where the lens 122 is set on the transparent resin 120b. By receiving the overflowing transparent resin 120c outside the reflecting portion 118 (or the gap formed between the reflecting portion 118 and the lead frame 100), the influence on the mountability of the lens 122 can be prevented.

  Next, a more detailed description will be given with reference to FIG. FIG. 6 is a perspective view of the reflecting portion. In FIG. 6, the light emitting element 108 and the lead frame 100 mounted in the reflecting portion 118 are not shown. 124 is a groove, and 126 is a protrusion.

  As shown in FIG. 6A, by forming a groove portion 124 in a part of the reflecting portion 118, when the transparent resin 120 is added using a dispenser or the like as indicated by an arrow 110a, an excess transparent resin is used. 120 can be stored outside (portion described in FIGS. 5B and 5C) as indicated by an arrow 110b.

  In addition, as shown in FIG. 6B, by forming the projection 126 on a part of the reflection portion 118, the alignment can be ensured when the lens 122 is set as indicated by the arrow 110c. If necessary, a concave portion (not shown) corresponding to the protrusion 126 can be formed in the lens 122.

  Note that the transparent resin 120 that covers the light-emitting element 108 is preferably PMMA (polymethyl methacrylate) or a silicon-based transparent resin. When an epoxy resin is used here, it is necessary to add a UV inhibitor for preventing yellowing of the epoxy. This is because the LED is white, and further, the epoxy resin may be yellowed by blue light. Also, it is desirable to use a soft material such as silicon (having at least a lower hardness than epoxy). By using a soft (flexible) resin material, the light-emitting element 108 generates heat, and stress concentration at the connection portion between the light-emitting element 108 and the lead frame 100 when the thermal expansion occurs can be prevented. Similarly, stress concentration on the gold wire when the light emitting element 108 and the lead frame 100 are bonded and connected can be reduced (the gold wire is difficult to cut).

  Note that the light-emitting element 108 mounted on the light-emitting module is preferably a light-emitting element having at least one kind of different emission colors. Color rendering properties can be improved by using a plurality of light emitting elements 108 having different light emission colors, and the color mixing properties of each other can be improved by mounting a plurality of these in a region surrounded by one light reflector. It is done. In addition, one or more emission colors of the plurality of light emitting elements 108 may be white. As described above, in the configuration of the second embodiment, by taking advantage of the excellent heat dissipation, even the light emitting element 108 whose light emission efficiency is easily affected by the temperature (or the degree of influence is different) can be affected by the temperature. It is hard to receive. Further, it goes without saying that even when the temperature of the light emitting module itself rises, the light emission amount of the light emitting element 108 can be individually controlled via the lead frame 100.

(Embodiment 3)
Hereinafter, an example of another method for manufacturing the light emitting module according to Embodiment 3 of the present invention will be described with reference to FIG. FIG. 7 is a cross-sectional view showing an example of a method for manufacturing a light emitting module in the third embodiment. The difference between the second embodiment and the third embodiment is that the light reflecting material 104 covers the top and bottom and side surfaces of the lead frame 100 (corresponding to the third embodiment), and the top and side surfaces of the lead frame 100 are light reflecting material. 104 (corresponding to the second embodiment). As shown in the third embodiment, the upper and lower sides and the side surfaces of the lead frame 100 are also covered with the light reflecting material 104, so that the lead frame 100 can be prevented from being deformed and the lead frame 100 and the metal plate 112 can be prevented from being short-circuited. This is because the lead frame 100 and the metal plate 112 are insulated by the multilayer of the light reflecting material 104 and the heat conductive resin 102.

  FIG. 7A is a cross-sectional view of the lead frame 100. Next, as shown in FIG. 7B, the back and front of the lead frame 100 are fixed by the light reflecting material 104. In this step, a technique such as injection molding can be used. In this way, deformation of the lead frame 100 can be prevented. At the same time, the reflection portion 118 can be formed. Further, the light reflecting material 104 can be embedded in the back surface (the heat conducting resin 102 side) of the lead frame 100. In this way, a part of the light reflecting material 104 can be formed in a gap between the lead frames 100 and at a position between the lead frame 100 and the heat conductive resin 102 so as to avoid a position directly below the light emitting element 118. The reason why the light reflecting material 104 is not formed under the lead frame 100 immediately below the light emitting element 118 is that the heat conduction from the lead frame 100 to the heat conducting resin 102 is not affected.

  Next, as shown in FIG. 7C, a part of the lead frame 100 is bent. Then, it is integrated with the metal plate 112 using the heat conductive resin 102. In this integral molding, a hot press or the like can be used. Note that the order of FIGS. 7B and 7C (that is, the bending of the lead frame 100 and the molding of the light reflecting material 104) can be switched.

  The lead frame 100 fixed with the light reflecting material 104 and the heat conducting resin 102a are integrated by first preliminarily molding the heat conducting resin 102a and the lead frame 100 (or pregel or pregel molding), and then FIG. As shown, the metal plate 112 may be pressed in the direction of arrow 110 and heat cured. When molding as shown in FIG. 7D, in order to prevent the generation of voids between the metal plate 112 and the heat conducting resin 102a (the void is an air layer generated due to insufficient adhesion, etc.) For example, the central portion of the heat conducting resin 102a is thickened or made into a bowl shape to prevent air remaining. As shown in FIG. 7D, the heat conducting resin 102b is made to wrap around to the side surface of the light reflecting material 104 to be molded, thereby increasing the adhesive strength between the reflecting portion 118 formed of the light reflecting material 104 and the heat conducting resin 102b. It is done. Then, after mounting the light emitting element 108, a transparent resin 120 is injected. At this time, the overflowing transparent resin 120 b has a mechanism for collecting in the recess formed between the light reflecting material 104 and the lead frame 100, thereby improving the stability of the process.

  As shown in FIG. 7E, the light emitting element 108 is mounted and dip protected with a transparent resin 120a. At this time, even if the amount of the transparent resin 120b varies somewhat, the outside of the reflecting portion 118 can be used as an extra resin buffer portion, so that stable manufacturing can be realized.

(Embodiment 4)
Hereinafter, an example of the manufacturing method of the light emitting module in Embodiment 4 of this invention is demonstrated using FIG.

  FIG. 8 is a cross-sectional view showing an example in which the thickness of the heat conducting resin is controlled using the shape of the light reflecting material.

  FIG. 8A is a cross-sectional view showing an example of the shape of the light reflecting material 104 formed on the lead frame 100. The upper portion of the light reflecting material 104 is exposed upward from the lead frame 100 so that the reflecting portion 118 is formed. The lower part of the light reflecting material 104 is exposed downward from the lead frame 100 and is fitted with a metal plate 112 (and further controls the thickness of the heat conductive resin 102 filled between the metal plate 112 and the lead frame 100). Part 128. Then, the light reflecting material 104 is combined with the lead frame 100 using a technique such as injection molding as indicated by an arrow 110a.

  FIG. 8B is a cross-sectional view showing a state in which the light reflecting material 104 and the lead frame 100 are integrated. In FIG. 8B, a reflection portion 118 that reflects light emitted from a light emitting element (not shown) is formed on the lead frame 100. A spacer portion 128 is formed under the lead frame 100 to fit the metal plate 112 (and control the thickness of the heat conducting resin 102 filled between the metal plate 112 and the lead frame 100).

  FIG. 8C is a cross-sectional view showing a state in which the lead frame 100 and the metal plate 112 are integrated using the heat conductive resin 102. The lead frame 100 on which the light reflecting material 104 is molded using a mold (not shown) and the metal plate 112 are integrally molded with the heat conductive resin 102 by a method indicated by an arrow 110b.

  FIG. 8D is a cross-sectional view after being integrally molded, and the gap between the metal plate 112 and the lead frame 100 is made constant by the spacer portion 128 formed by the light reflecting material 104, and the heat conducting resin 102 therebetween. Is filled. By filling the heat conductive resin 102 between the metal plate 112 and the spacer portion 128 in this way, the heat conductive resin 102 can be made thin and uniform, and the efficiency of heat conduction to the metal plate 112 can be improved. Can do.

  Thus, by covering a part of the light reflecting material 104 not only on the side surface but also the back surface of the lead frame 100, the lead frame 100 can be fixed securely, and the lead frame 100 and the metal plate 112 can be short-circuited. Therefore, the heat conducting resin 102 can be thinned.

  8B and 8C may be bent after the integration step using the heat conductive resin 102.

  Then, by forming a part of the light reflecting material 104 as a spacer that holds the gap between the lead frame 100 and the metal plate 112, the molding accuracy of the heat conductive resin 102 between the lead frame 100 and the metal plate 112 can be improved.

Next, the insulating material will be described in more detail. The heat conducting resin 102 is composed of a filler and a resin. The filler is preferably an inorganic filler. As the inorganic filler, it is desirable to have one containing at least one selected from the group consisting of Al ₂ O ₃ , MgO, BN, SiO ₂ , SiC, Si ₃ N ₄ , and AlN. When an inorganic filler is used, heat dissipation can be improved, but when using MgO in particular, the linear thermal expansion coefficient can be increased. Further, when SiO ₂ is used, the dielectric constant can be reduced, and when BN is used, the linear thermal expansion coefficient can be reduced. In this way, the heat conductive resin 102 having a thermal conductivity of 1 W / (m · K) or more and 20 W / (m · K) or less can be formed. In addition, when heat conductivity is less than 1 W / (m * K), it influences the heat dissipation of a light emitting module. Moreover, when it is going to make thermal conductivity higher than 20 W / (m * K), it is necessary to increase the amount of fillers and may affect the workability at the time of a press.

  The resin is preferably a thermosetting resin, and specifically includes at least one selected from the group consisting of an epoxy resin, a phenol resin, and an isocyanate resin.

The inorganic filler has a substantially spherical shape and a diameter of 0.1 to 100 μm. The smaller the particle size, the better the filling rate into the resin. Therefore, the filling amount (or content) of the inorganic filler in the heat conductive resin 102 is filled at a high concentration of 70 to 95% by weight in order to increase the heat conductivity. In particular, in the present embodiment, the inorganic filler is a mixture of two types of Al ₂ O ₃ having an average particle size of 3 microns and an average particle size of 12 microns. By using the Al ₂ O ₃ of the large and small two types of particle size, it is possible to fill the Al ₂ O ₃ of small particle size in the gap Al ₂ O ₃ of large particle size, Al ₂ O ₃ 90 wt% near Can be filled to a high concentration. As a result, the thermal conductivity of the heat conducting resin 102 is about 5 W / (m · K). In addition, when the filling rate of a filler is less than 70 weight%, thermal conductivity may fall. Further, if the filling rate (or content rate) of the filler exceeds 95% by weight, the moldability of the heat conducting resin 102 before curing may be affected, and the adhesion between the heat conducting resin 102 and the lead frame 100 (for example, when embedded) Or if it is attached to the surface).

  The thermosetting insulating resin contains at least one kind of resin among epoxy resin, phenol resin and cyanate resin. These resins are excellent in heat resistance and electrical insulation.

  If the thickness of the insulator made of the heat conducting resin 102 is reduced, the heat generated in the light emitting element 108 attached to the lead frame 100 can be easily transferred to the metal plate 112, but conversely, the withstand voltage becomes a problem. Since the thermal resistance increases, the optimum thickness may be set in consideration of the withstand voltage and the thermal resistance.

  Next, the material of the lead frame 100 will be described. The lead frame is preferably made mainly of copper. This is because copper has both excellent thermal conductivity and electrical conductivity. In order to improve the workability and thermal conductivity as a lead frame, the copper material used as the lead frame 100 is selected from a group of at least Sn, Zr, Ni, Si, Zn, P, Fe, etc. other than copper. It is desirable to use an alloy comprising at least one material. For example, an alloy (hereinafter referred to as Cu + Sn) in which Cu is a main component and Sn is added thereto can be used. In the case of a Cu + Sn alloy, for example, by adding Sn to 0.1 wt% or more and less than 0.15 wt%, the softening temperature can be increased to 400 ° C. For comparison, when the lead frame 100 was manufactured using Sn-free copper (Cu> 99.96 wt%), the electrical conductivity was low. It was. Therefore, when the detailed examination was made, the softening point of the material was as low as about 200 ° C., so when the component was later mounted (soldering) or when the reliability after the light-emitting element 108 was mounted (repetition test of heat generation / cooling) Etc.). On the other hand, when a copper-based material with Cu + Sn> 99.96 wt% was used, it was not particularly affected by the heat generated by various mounted components and a plurality of LEDs. There was no effect on solderability and die bondability. Therefore, when the softening point of this material was measured, it was found to be 400 ° C. Thus, it is desirable to add some elements mainly composed of copper. In the case of Zr as an element added to copper, a range of 0.015 wt% or more and 0.15 wt% or less is desirable. When the amount added is less than 0.015 wt%, the effect of increasing the softening temperature may be small. On the other hand, if the amount added is more than 0.15 wt%, the electrical characteristics may be affected. Also, the softening temperature can be increased by adding Ni, Si, Zn, P or the like. In this case, Ni is preferably 0.1 wt% or more and less than 5 wt%, Si is 0.01 wt% or more and 2 wt% or less, Zn is 0.1 wt% or more and less than 5 wt%, and P is preferably 0.005 wt% or more and less than 0.1 wt%. . And these elements can make the softening point of a copper raw material high by adding single or multiple in this range. In addition, when there are few addition amounts than the ratio described here, the raise effect of a softening point may be low. Moreover, when there are more than the ratio described here, there exists a possibility of affecting the electrical conductivity. Similarly, in the case of Fe, 0.1 wt% or more and 5 wt% or less is desirable, and in the case of Cr, 0.05 wt% or more and 1 wt% or less are desirable. These elements are the same as those described above.

The tensile strength of the copper alloy used for the lead frame 100 is desirably 600 N / mm ² or less. In the case of a material having a tensile strength exceeding 600 N / mm ² , the workability of the lead frame 100 may be affected. Further, such a material having a high tensile strength tends to increase its electric resistance, so that it may not be suitable for high current applications such as LEDs used in the first embodiment. On the other hand, if the tensile strength is 600 N / mm ² or less (and if the lead frame 100 requires fine and complicated processing, it is preferably 400 N / mm ² or less). Excluding, it is possible to suppress the occurrence of rebound to the original position by the reaction force, and to improve the formation accuracy. As described above, as the lead frame material, the electrical conductivity can be lowered by using Cu as a main component, the workability can be improved by further softening, and the heat dissipation effect by the lead frame 100 can also be enhanced. The tensile strength of the copper alloy used for the lead frame 100 is desirably 10 N / mm ² or more. This is because the copper alloy used for the lead frame 100 needs to have a strength higher than the tensile strength (about 30 to 70 N / mm ² ) of general lead-free solder. When the tensile strength of the copper alloy used for the lead frame 100 is less than 10 N / mm ² , when the light emitting element 108, the driving semiconductor component, the chip component, etc. are soldered and mounted on the lead frame 100, the lead frame is not the solder portion. There is a possibility of cohesive failure at 100 parts.

  It should be noted that the solder layer so as to improve the solderability in advance on the surface of the lead frame 100 exposed from the heat conductive resin 102 (the light emitting element 108 or a mounting surface of a control IC or chip component (not shown)). By forming a tin layer, it is possible to improve component mounting on the lead frame 100, which has a larger heat capacity than a glass epoxy substrate or the like and is difficult to solder, and to prevent rusting of the wiring. It is desirable that no solder layer be formed on the surface of the lead frame 100 that is in contact with the heat conductive resin 102 (or the embedded surface). When a solder layer or a tin layer is formed on the surface in contact with the heat conducting resin 102 in this way, this layer becomes soft during soldering, which may affect the adhesion (or bond strength) between the lead frame 100 and the heat conducting resin 102. . 1 and 2, the solder layer and the tin layer are not shown.

The metal metal plate 112 is made of aluminum, copper, or an alloy containing them as a main component, which has good thermal conductivity. In particular, in the present embodiment, the thickness of the metal plate 112 is 1 mm, but the thickness can be designed according to the specifications of a backlight or the like (in addition, when the thickness of the metal plate 112 is 0.1 mm or less, heat dissipation and (If the thickness of the metal plate 112 exceeds 50 mm, it is disadvantageous in terms of weight.) The metal plate 112 is not only a plate-like material, but also has a fin portion (or uneven portion) to increase the surface area on the surface opposite to the surface on which the insulators are laminated in order to further improve heat dissipation. You may do it. The linear expansion coefficient is 8 × 10 ⁻⁶ / ° C. to 20 × 10 ⁻⁶ / ° C. By bringing the linear expansion coefficient close to the linear expansion coefficients of the metal plate 112 and the light emitting element 108, warpage and distortion of the entire substrate can be reduced. In addition, when these components are surface-mounted, matching the thermal expansion coefficients with each other is also important in terms of reliability. Further, the metal plate 112 can be screwed to another heat radiating plate (not shown).

  As the lead frame 100, a metal plate mainly made of copper, at least a part of which is punched in advance, can be used. The thickness of the lead frame 100 is desirably 0.1 mm or greater and 1.0 mm or less (more desirably 0.3 mm or greater and 0.5 mm or less). This is because a large current (for example, 30 A to 150 A, which may further increase depending on the number of LEDs to be driven) is required to control the LEDs. Moreover, when the thickness of the lead frame 100 is less than 0.10 mm, pressing may be difficult. If the thickness of the lead frame 100 exceeds 1 mm, pattern miniaturization may be affected at the time of punching with a press. Here, it is not desirable to use a copper foil (for example, a thickness of 10 to 50 microns) instead of the lead frame 100. In the case of the present invention, the heat generated in the LED is widely diffused through the lead frame 100. Therefore, the greater the thickness of the lead frame 100, the more effective the thermal diffusion through the lead frame 100. On the other hand, when a copper foil is used instead of the lead frame 100, the thickness of the copper foil is thinner than that of the lead frame, which may make it difficult for heat diffusion.

  Furthermore, by devising a temperature profile when the heat conducting resin 102 and the lead frame 100 are heated and pressed, the heat conducting resin 102 can be softened (decrease in viscosity), and the influence on the lead frame 100 can also be suppressed. In this way, the light emitting module using the lead frame 100 having a large thickness and excellent heat dissipation by separately dividing the molding process of the lead frame 100 and the molding process of the lead frame 100 and the heat conductive resin 102 which are molded in advance. Can be formed at low cost.

  In this way, the lead frame 100 mainly composed of copper having the ring-shaped first convex portion 114 and a part thereof being fixed by the light reflecting material, and the metal plate 112 having the ring-shaped second convex portion 116, The ring-shaped first protrusion is made of a heat conductive resin 102 which is an insulating layer made of an inorganic filler formed between the lead frame 100 and the metal plate 112 and a resin composition containing a thermosetting resin. A light emitting module having a structure in which a part of light emitted from the light emitting device 108 mounted on the lead frame 100 surrounded by the portion 114 is reflected by the reflecting portion 118 formed of the light reflecting material 104 is provided.

  In addition, a lead frame 100 mainly composed of copper having a ring-shaped first convex portion 114 and a part thereof being fixed by the light reflecting material 104, and a metal plate 112 having a ring-shaped second convex portion 116. And a heat conductive resin 102 that is an insulating layer made of an inorganic filler formed between the lead frame 100 and the metal plate 112 and a resin composition containing a thermosetting resin. A portion of the transparent resin 120 that protects the light emitting element 108 mounted on the lead frame 100 surrounded by the convex portion 114 is formed between the reflective portion 108 formed on the lead frame 100 and the lead frame 100. Provided is a light emitting module having a structure of accumulating in a gap.

  Moreover, between the lead frame 100 which has the ring-shaped 1st convex part 114 and one part is being fixed with the light reflection material 104, and the metal plate 112 which has a ring-shaped 2nd convex part 116, The insulating resin 102 is cured in a state where the heat conducting resin 102 which is an insulating resin is sandwiched, and the metal plate 112 and the lead frame 100 fixed by the light reflecting material 104 are integrated. A method of manufacturing a light emitting module is provided in which a light emitting element is mounted on the lead frame 100 exposed in a portion surrounded by a circle.

  Moreover, between the lead frame 100 which has the ring-shaped 1st convex part 114 and one part is being fixed with the light reflection material 104, and the metal plate 112 which has a ring-shaped 2nd convex part 116, The heat conducting resin 102 is cured with the heat conducting resin 102 as an insulating resin interposed therebetween, and the metal plate 112 and the lead frame 100 fixed by the light reflecting material 104 are integrated. Provided is a method for manufacturing a light emitting module in which a light emitting element 108 is mounted on the lead frame 100 exposed in a portion surrounded by a transparent resin 120 and covered with a transparent resin 120.

As the light reflecting material 104, white ceramic powder such as TiO ₂ or MgO, or light reflecting powder having high light reflection such as glass powder or micro glass beads is dispersed in a thermoplastic resin having high heat resistance. Can be used. Various members are commercially available for surface mounting LEDs, and such members can be used. In addition, as a method of molding such a commercially available light reflecting material 104 with the lead frame 100, a material having high mass productivity such as injection molding can be selected. Note that the light reflectance in the visible light region of the light reflecting material 104 is desirably 90% or more and 99.9% or less. When the light reflectance is less than 90%, the reflection efficiency at the reflecting portion 118 is affected. Further, if the light reflectance is made higher than 99.9%, the light reflecting material 104 may become very expensive. The light reflecting material 104 is preferably white. By making it white, color mixing of monochromatic light such as Red, Green, Blue, etc. is facilitated.

  Further, the light emitting element 108 is mounted on the lead frame 100 within an area surrounded by the light reflecting material 104, and further covered with a transparent resin 120b or the like, so that the light emitting element 108 can be protected and the plurality of light emitting elements 108 can be protected. High-density bare mounting is possible. In addition, by mounting a plurality of light emitting elements 108 at a high density, it becomes easy to uniformize white color due to color mixing.

  In addition, as the light reflection material 104, it can carry out injection molding, for example using what disperse | distributed the white pigment in polycarbonate resin. In particular, in the case of polycarbonate resin, it is desirable that the resin is sufficiently dried before injection molding. This is because the polycarbonate resin is a hydrophilic resin and absorbs moisture in the air. Therefore, if injection molding is performed without drying, a hydrolysis reaction of the resin may occur during molding, and the molecular weight of the resin may decrease, affecting the quality of the molded body. Therefore, drying is preferably performed at 100 ° C. or higher (desirably 110 ° C. to 130 ° C. for 4 to 6 hours). The molding temperature is preferably in the range of 250 ° C to 300 ° C, and the mold temperature is preferably in the range of 50 ° C to 120 ° C. If the temperature is lower than this range, the moldability may be affected. When the molding temperature is higher than this range, the moldability and the physical properties of the resin of the molded body may be affected.

In addition, PPS and liquid crystal polymer can be selected as the resin for the light reflecting material 104. In the case of such a resin (for example, a liquid crystal polymer), the injection temperature is around 340 ° C. (desirably 270 ° C. or more and 380 ° C. or less. If the temperature range is lower than this temperature range, the injection moldability may be affected. May affect the resin properties). Similarly, the mold is heated to around 100 ° C. (preferably 50 ° C. or more and 130 ° C. or less, which may affect the moldability if it is lower than this temperature range. The same applies if it is higher than this temperature range). It is desirable to do. Examples of the white pigment to be added here may be used _{TiO 2, Al 2 O 3,} MgO or the like. The particle diameter of these pigments is preferably 10 microns or less and 0.01 microns or more (preferably 5 microns or less and 0.1 microns or more). If it is larger than 10 microns, the moldability may be affected. On the other hand, when the particle size is less than 0.01 micron, the specific surface area of the powder becomes too large, which may affect the fluidity during injection molding.

  As described above, since the light emitting module according to the present invention can be used to stably light a large number of light emitting elements, in addition to backlights such as liquid crystal TVs, projectors, projectors, etc. It can also be applied to color rendering applications.

Top view and cross-sectional view illustrating a light-emitting module according to Embodiment 1 Diagram showing the shape of the lead frame Diagram showing how heat diffuses Sectional drawing which shows an example of the manufacturing method of the light emitting module in Embodiment 2. Sectional drawing which shows an example of the manufacturing method of the light emitting module in Embodiment 2. Reflective part perspective view Sectional drawing which shows an example of the manufacturing method of the light emitting module in Embodiment 3. Sectional drawing which shows an example which performs thickness control of heat conductive resin using the shape of a light reflection material Sectional drawing which shows an example of the conventional light emitting module

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Lead frame 102 Thermal conductive resin 104 Light reflecting material 106 Auxiliary line 108 Light emitting element 110 Arrow 112 Metal plate 114 1st convex part 116 2nd convex part 118 Reflective part 120 Transparent resin 122 Lens 124 Groove part 126 Protrusion part 128 Spacer part

Claims (18)

A lead frame mainly composed of copper having a ring-shaped first convex part and a part of which is fixed by a light reflecting material;
A metal plate having a ring-shaped second convex portion;
An insulating layer composed of an inorganic filler formed between the lead frame and the metal plate and a resin composition containing a thermosetting resin;
A light emitting module having a structure in which a part of light emitted from a light emitting element mounted on the lead frame surrounded by the first convex portion is reflected by a reflecting portion formed of the light reflecting material. A lead frame mainly composed of copper having a ring-shaped first convex part and a part of which is fixed by a light reflecting material;
A metal plate having a ring-shaped second convex portion;
An insulating layer made of an inorganic filler formed between the lead frame and the metal plate and a resin composition containing a thermosetting resin,
A structure in which a part of the transparent resin that protects the light emitting element mounted on the lead frame surrounded by the first convex portion is accumulated in a gap between the reflective portion formed on the lead frame and the lead frame. A light emitting module. 3. The light emitting module according to claim 1, wherein a thickness of the insulating layer formed between the metal plate and the lead frame is 50 μm or more and 500 μm or less. 3. The light emitting module according to claim 1, wherein the light reflecting material has a light reflectance of 90% or more and 99.9% or less in a visible light region in which light reflecting powder is dispersed in a resin. The light emitting module according to claim 1, wherein the light emitting element is mounted on the lead frame within an area surrounded by the light reflecting material and is further protected with a resin. The light emitting module according to claim 1, wherein a plurality of light emitting elements each having a different emission color are mounted in an area surrounded by a ring-shaped reflecting material. The light emitting module according to claim 1, wherein at least one of the plurality of light emitting elements has a white emission color. 2. The light emitting module according to claim 1, wherein the lead frame has a thickness of 0.10 mm to 1.0 mm, and at least a part of the lead frame is processed into a concave shape before being integrated with the insulating layer. The light emitting module according to claim 1, wherein the thermal conductivity of the insulating layer is 1 W / (m · K) or more and 20 W / (m · K) or less. _3. The light emitting module according to claim 1, wherein the inorganic filler includes at least one selected from the group consisting of Al ₂ O ₃ , MgO, BN, SiO ₂ , SiC, Si ₃ N ₄ , and AlN. The light emitting module according to claim 1, wherein the thermosetting resin includes at least one selected from the group consisting of an epoxy resin, a phenol resin, and an isocyanate resin. The light emitting module according to claim 1, wherein the insulating layer is white. The light emitting module according to claim 1, wherein the light reflecting material is white. Sn is 0.1 wt% to 0.15 wt%, Zr is 0.015 wt% to 0.15 wt%, Ni is 0.1 wt% to 5 wt%, Si is 0.01 wt% to 2 wt%, Zn is Lead frame mainly composed of copper containing at least one selected from the group of 0.1 wt% to 5 wt%, P is 0.005 wt% to 0.1 wt%, and Fe is 0.1 wt% to 5 wt%. The light emitting module according to claim 1, wherein the light emitting module is used. 3. The light emitting module according to claim 1, wherein a part of the light reflecting material is formed in a gap between the lead frames and a position between the lead frame and the insulating layer so as to avoid a position immediately below the light emitting element. . The light emitting module according to claim 1, wherein a part of the light reflecting material forms a spacer portion that holds a gap between the lead frame and the metal plate. A lead frame having a ring-shaped first convex portion, a part of which is fixed by a light reflecting material;
Between the metal plate having the ring-shaped second convex portion,
In a state where the insulating resin is sandwiched, the insulating resin is cured,
After integrating the metal plate and the lead frame fixed with a light reflecting material,
A method for manufacturing a light emitting module, wherein a light emitting element is mounted on the lead frame exposed in a portion surrounded by the light reflecting material. A lead frame having a ring-shaped first convex portion, a part of which is fixed by a light reflecting material;
Between the metal plate having the ring-shaped second convex portion,
In a state where the insulating resin is sandwiched, the insulating resin is cured,
After integrating the metal plate and the lead frame fixed with a light reflecting material,
A method of manufacturing a light emitting module, wherein a light emitting element is mounted on the lead frame exposed in a portion surrounded by the light reflecting material and covered with a transparent resin.

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